Certain fossilized carbon based materials such as fusinite and gloxy (coals) have been found to be very useful for EPR oximetry. These materials, however, do not have uniform properties and are difficult to obtain in large quantities. The manufacture of similar materials by heating of carbon (i.e. charcoals) has the potential of providing more uniform materials where properties may be optimized by varying the methods to produce them. An extreme program to produce and characterize such materials has been established at the University of Illinois. These materials then are tested for biological interactions at Dartmouth. The key properties being tested are effects on cells in suspension and properties when placed in tissues in living animals. A char derived from the Bubinga tree appears to have many of the desired properties.